It has been suggested for a long time to carry out a conching procedure by means of screws in a screw casing. The DE-C-288 770 represents an example for this. According to this proposal, four screws-- viewed in cross-section-- arranged along the sides of a rectangle are each accommodated in a screw casing, which process the chocolate paste in circulation. When using this arrangement it is stressed that it is essential to press the paste and to press the individual paste particles firmly against each other and to triturate them.
In fact, with the help of such screws a good refining effect can be achieved and high energy can be introduced into the mass. Probably this is the reason why screw devices are suggested for processing chocolate pastes again and again, although they have never really become important on the market. The reason for their lack of importance is presumably not least to be found in the fact that the conching work is not limited to the mere refining of chocolate pastes but that with conventional conching machines, as they have been suggested according to DE-B-1 189 368 with three rotors, a chemico-physical medium exchange is achieved in addition to this mere mechanical effect, since the radially extending blades of these rotors expose continually new surfaces of the chocolate paste under the effect of air, which, on the one hand, enables the intense access of oxygen, and, on the other hand, makes possible the escaping of vapors possibly contained in the paste.
It is an object of the invention to improve the kneading and refining of the paste of a conching machine of the conventional type mentioned above, as it is shown in the application mentioned last, while avoiding agglomerates or lumps, as they may develop e.g. by various ingredients, and thereby to shorten the often considerable conching time.